In a large bowl, sift together flour, 1 1/2 cups powdered sugar, cocoa, baking powder and salt and set aside. Combine chocolate and oil in a large, heavy saucepan over lowest heat, stirring frequently, until just melted and smooth; be very careful chocolate does not scorch. Remove from heat, and let cool slightly. Stir in corn syrup, brown sugar and vanilla until well blended. Beat egg whites into chocolate mixture and stir until brown sugar dissolves. Gently stir dry ingredients into chocolate mixture just until well blended and smooth. Cover dough and refrigerate until firm enough to shape into balls (at least 2 1/2 hours). Preheat oven to 350 degrees. Grease and flour several baking sheets. Place powdered sugar for coating balls in a medium-sized shallow bowl. With lightly oiled hands, roll portions of dough into 1-inch balls between palms. Roll each ball in powdered sugar until heavily coated. Arrange balls on baking sheets about 1 1/2 inches apart. Bake on middle oven rack for 8 to 10 minutes or until center tops are almost firm when tapped. Let stand about 2 minutes until cookies firm up slightly. transfer cookies to wire racks. Let stand until thoroughly cooled. Enjoy. (Makes about 4 dozen cookies)